Optical Constants of Electrodeposited Mixed Molybdenum-Tungsten Oxide Films Determined by Variable-Angle Spectroscopic Ellipsometry

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• 作者：R. Alan May ; Lilia Kondrachova ; Benjamin P. Hahn ; Keith J. Stevenson
• 刊名：Journal of Physical Chemistry C
• 出版年：2007
• 出版时间：December 13, 2007
• 年：2007
• 卷：111
• 期：49
• 页码：18251 - 18257
• 全文大小：495K
• 年卷期：v.111,no.49(December 13, 2007)
• ISSN：1932-7455

文摘

Mixed molybdenum-tungsten oxides of varying stoichiometry (Mo_xW_1-xO₃, 0 < x < 1) prepared by cathodicelectrodeposition from aqueous peroxo-polymolybdotungstate solutions on indium tin oxide (ITO) coatedglass substrates were evaluated by variable-angle spectroscopic ellipsometry (VASE) and transmissionmeasurements from 200 to 1000 nm (1.24-6.2 eV). A Tauc-Lorentz dispersion model was used to determinethe real and imaginary components of the complex refractive index for Mo_xW_1-xO₃ films as a function of Mofraction. The optical band gaps were also estimated from Tauc plots. The refractive index increased (2.07-2.20 at 800 nm) while the optical band gap decreased (3.38-2.95 eV) in a linear fashion for Mo_xW_1-xO₃films with increasing Mo fraction. These trends correlate chiefly with Mo-doping-induced changes in filmstructure and grain size as supported by X-ray diffraction measurements.